And once women are up, they’re awake for an average of 44 minutes, compared to 30 minutes for men.

Women might be getting out of bed to tend to a hungry pet or an elderly parent but most often they’re caring for a child, especially a young one.

The Washington Post reports: “Among dual-income couples with a child younger than 1, 32 percent of women reported sleep interruptions on a given 24-hour period, compared with 11 percent of men. For those with children ages 3 to 5, 3 percent of mothers and 1 percent of fathers experienced interrupted sleep.”

You might think a woman would be less likely to interrupt her sleep if she were the family’s sole breadwinner–maybe dad would be more likely to help her out in the middle of the night. That isn’t the case. “Among parents of children younger than 1, 28 percent of women who were the sole earner in the couple reported getting up in the middle of the night to take care of children, compared with 4 percent of men who were the sole breadwinner,” according to the Post.

“Obviously, the child-rearing responsibilities maybe slanted at first due to breast-feeding, but then the responsibilities are never renegotiated,” the study’s lead researcher, Sarah Burgard, an assistant professor of sociology and epidemiology at the University of Michigan School of Public Health in Ann Arbor, told the Post.

If you’re a mother then you’re probably not surprised by any of this. When my children were newborns, I remember waking up to every little cry while my husband slept soundly through even the loudest wails. And now that my kids are ages 6 and 7, I’m still the first one to pop out of bed when one of them has a nightmare or gets sick in the middle of the night.

I could call my husband lazy, sexist and insensitive but his failure to hear a crying child while he’s sleeping might not be his fault at all. Researchers have actually found that women are hard-wired to wake up to the sound of a sobbing baby. A 2009 study by the British Mindlab sleeping lab found that a baby’s crying is the number one sound most likely to rouse a woman and didn’t even factor into the male top 10. Men were more likely to wake to the sounds of a car alarm, howling wind, or a buzzing fly.

I can’t complain. The other night I immediately woke up when my daughter got sick at 2 a.m., while my husband slept through the sound of her crying and retching. But when I roused him to ask for help, he grabbed the mop and bucket and cleaned the mess up while I consoled my tearful child.

Who gets up in your family when a kid is crying in the middle of the night?